icuSources/common/locdistance.h

   1 // © 2019 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html#License
   3
   4 // locdistance.h
   5 // created: 2019may08 Markus W. Scherer
   6
   7 #ifndef __LOCDISTANCE_H__
   8 #define __LOCDISTANCE_H__
   9
  10 #include "unicode/utypes.h"
  11 #include "unicode/bytestrie.h"
  12 #include "unicode/localematcher.h"
  13 #include "unicode/locid.h"
  14 #include "unicode/uobject.h"
  15 #include "lsr.h"
  16
  17 U_NAMESPACE_BEGIN
  18
  19 struct LocaleDistanceData;
  20
  21 /**
  22  * Offline-built data for LocaleMatcher.
  23  * Mostly but not only the data for mapping locales to their maximized forms.
  24  */
  25 class LocaleDistance final : public UMemory {
  26 public:
  27     static const LocaleDistance *getSingleton(UErrorCode &errorCode);
  28
  29     /**
  30      * Finds the supported LSR with the smallest distance from the desired one.
  31      * Equivalent LSR subtags must be normalized into a canonical form.
  32      *
  33      * <p>Returns the index of the lowest-distance supported LSR in bits 31..8
  34      * (negative if none has a distance below the threshold),
  35      * and its distance (0..ABOVE_THRESHOLD) in bits 7..0.
  36      */
  37     int32_t getBestIndexAndDistance(const LSR &desired,
  38                                     const LSR **supportedLSRs, int32_t supportedLSRsLength,
  39                                     int32_t threshold, ULocMatchFavorSubtag favorSubtag) const;
  40
  41     int32_t getParadigmLSRsLength() const { return paradigmLSRsLength; }
  42
  43     UBool isParadigmLSR(const LSR &lsr) const;
  44
  45     int32_t getDefaultScriptDistance() const {
  46         return defaultScriptDistance;
  47     }
  48
  49     int32_t getDefaultDemotionPerDesiredLocale() const {
  50         return defaultDemotionPerDesiredLocale;
  51     }
  52
  53 private:
  54     LocaleDistance(const LocaleDistanceData &data);
  55     LocaleDistance(const LocaleDistance &other) = delete;
  56     LocaleDistance &operator=(const LocaleDistance &other) = delete;
  57
  58     static void initLocaleDistance(UErrorCode &errorCode);
  59
  60     static int32_t getDesSuppScriptDistance(BytesTrie &iter, uint64_t startState,
  61                                             const char *desired, const char *supported);
  62
  63     static int32_t getRegionPartitionsDistance(
  64         BytesTrie &iter, uint64_t startState,
  65         const char *desiredPartitions, const char *supportedPartitions,
  66         int32_t threshold);
  67
  68     static int32_t getFallbackRegionDistance(BytesTrie &iter, uint64_t startState);
  69
  70     static int32_t trieNext(BytesTrie &iter, const char *s, bool wantValue);
  71
  72     const char *partitionsForRegion(const LSR &lsr) const {
  73         // ill-formed region -> one non-matching string
  74         int32_t pIndex = regionToPartitionsIndex[lsr.regionIndex];
  75         return partitionArrays[pIndex];
  76     }
  77
  78     int32_t getDefaultRegionDistance() const {
  79         return defaultRegionDistance;
  80     }
  81
  82     // The trie maps each dlang+slang+dscript+sscript+dregion+sregion
  83     // (encoded in ASCII with bit 7 set on the last character of each subtag) to a distance.
  84     // There is also a trie value for each subsequence of whole subtags.
  85     // One '*' is used for a (desired, supported) pair of "und", "Zzzz"/"", or "ZZ"/"".
  86     BytesTrie trie;
  87
  88     /**
  89      * Maps each region to zero or more single-character partitions.
  90      */
  91     const uint8_t *regionToPartitionsIndex;
  92     const char **partitionArrays;
  93
  94     /**
  95      * Used to get the paradigm region for a cluster, if there is one.
  96      */
  97     const LSR *paradigmLSRs;
  98     int32_t paradigmLSRsLength;
  99
 100     int32_t defaultLanguageDistance;
 101     int32_t defaultScriptDistance;
 102     int32_t defaultRegionDistance;
 103     int32_t minRegionDistance;
 104     int32_t defaultDemotionPerDesiredLocale;
 105 };
 106
 107 U_NAMESPACE_END
 108
 109 #endif  // __LOCDISTANCE_H__